Nanda Devi National Park covers an area of 630.33 km2 and together with Valley of Flowers National Park is encompassed in the Nanda Devi Biosphere Reserve totaling a protected area of 2,236.74 km2, which is surrounded by a buffer zone of 5,148.57 km2. This Reserve is part of the UNESCO World Network of Biosphere Reserves since 2004.

The park encompasses the Nanda Devi Sanctuary, a glacial basin surrounded by a ring of peaks between 6,000 metres and 7,500 metres high, and drained by the Rishi Ganga through the Rishi Ganga Gorge, a steep, almost impassable defile. The entire park lies at an elevation of more than 3,500 metres above mean sea level.

Geography

The sanctuary can be divided into two parts, Inner and Outer. Together, they are surrounded by the main sanctuary wall, which forms a roughly square outline, with high, continuous ridges on the north, east, and south sides. On the west side, less high but still imposing ridges drop from the north and south toward the Rishi Ganga Gorge, which drains the sanctuary towards the west. The Inner Sanctuary occupies roughly the eastern two-thirds of the total area, and contains Nanda Devi itself and the two major glaciers flanking the peak, the Uttari (north) Rishi Glacier and the Dakshini (south) Rishi Glacier. These are fed by the smaller Uttari Nanda Devi and Dakshini Nanda Devi Glaciers respectively. The Outer Sanctuary occupies the western third of the total sanctuary, and is separated from the Inner Sanctuary by high ridges, through which flows the Rishi Ganga. It is split in two by the Rishi Ganga; on the north side lies the Ramani Glacier, flowing down from the slopes of Dunagiri and Changabang, and on the south lies the Trisul Glacier, flowing from the peak of the same name. This portion of the sanctuary is accessible to the outside (though requiring the crossing of a 4,000 metre pass. The first serious climbing expedition to pass through the Outer Sanctuary was that of T. G. Longstaff, who climbed Trisul I in 1907 via the eponymous glacier